"stevej" wrote
I have a Cordyline, I think it is an Australis and it's just a nice size
and shape. Can either potting it or clipping the roots slow it down
without harming it ?

Steve, the roots are busy making their way home so your chance of pruning
them or successfully digging up the plant to pot it are rather small.
They look better as they get older and bigger IMO, especially once they have
split into a nice head and flower each year.

--
Regards
Bob Hobden
17mls W. of London.UK